Add feature that allows references to synthetic properties with warning

See KT-35933 for details

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -784,6 +784,8 @@ public interface Errors {
     DiagnosticFactory0<KtExpression> NULLABLE_TYPE_IN_CLASS_LITERAL_LHS = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory1<KtExpression, KotlinType> EXPRESSION_OF_NULLABLE_TYPE_IN_CLASS_LITERAL_LHS = DiagnosticFactory1.create(ERROR);
 
+    DiagnosticFactory0<PsiElement> CALLABLE_REFERENCE_TO_JAVA_SYNTHETIC_PROPERTY = DiagnosticFactory0.create(WARNING);
+
     // Destructuring-declarations
 
     DiagnosticFactory0<KtDestructuringDeclaration> INITIALIZER_REQUIRED_FOR_DESTRUCTURING_DECLARATION = DiagnosticFactory0.create(ERROR, DEFAULT);

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -965,6 +965,8 @@ public class DefaultErrorMessages {
         MAP.put(NULLABLE_TYPE_IN_CLASS_LITERAL_LHS, "Type in a class literal must not be nullable");
         MAP.put(EXPRESSION_OF_NULLABLE_TYPE_IN_CLASS_LITERAL_LHS, "Expression in a class literal has a nullable type ''{0}'', use !! to make the type non-nullable", RENDER_TYPE);
 
+        MAP.put(CALLABLE_REFERENCE_TO_JAVA_SYNTHETIC_PROPERTY, "References to the synthetic extension properties for a Java get/set methods aren't supported fully, please use reference to a method");
+
         //Inline
         MAP.put(NON_PUBLIC_CALL_FROM_PUBLIC_INLINE, "Public-API inline function cannot access non-public-API ''{0}''", SHORT_NAMES_IN_TYPES, SHORT_NAMES_IN_TYPES);
         MAP.put(PRIVATE_CLASS_MEMBER_FROM_INLINE, "Non-private inline function cannot access members of private classes: ''{0}''", SHORT_NAMES_IN_TYPES, SHORT_NAMES_IN_TYPES);